Another journal rejection! Boo-hoo!

A week and a half after having a paper accepted by the European Journal on Operational Research, one of my other papers was rejected by the same journal. :(

The rejected paper talks about a class of techniques for the Single Container Loading Problem (SCLP) which asks: given a bunch of boxes, how do you load them into a container so that the least space is wasted? Problems don't get much more basic than that, and as you can imagine, it's pretty well studied. In our paper, we managed to beat the best existing results on benchmark data by a significant margin, which is quite a feat.

So why was the paper rejected? Well, part of the problem is that we achieved the best results without adding any ground-breaking, earth-shaking new technique. What we did was essentially analyze what other people did, mixed and matched the parts that seemed effective and tweaked it a little bit. That sounds simple, but in reality it takes a lot of hard work. We had to re-implement some really complicated methods and went down lots of blind alleys. Eventually, we realized that many things that existing literature assumed was effective, well, didn't work.

For example, most approaches spend a lot of effort using some fancy search technique to decide which box to place where. It turns out that these fancy search techniques don't perform better than simple ones. Unfortunately, the previous approaches were so complicated that it was hard to figure out why it worked, so many researchers thought it was the fancy search doing the work when in reality it was something else.

After a lo-o-o-t of experiments and analysis, we identified six "key elements" for this type of SCLP approach that we believe are essential. "Cool," we thought, "now we can put the research community back on track so that they know how to better design their algorithms. This is really useful!" We wrote it up into a paper, used our method as an example, and submitted it for review by the scientific community...

...and got repeatedly shot down. There were a few reviewers who loved it, but there were always a few who rejected it on the spot. The two most common criticisms were (1) the six elements are "well known", and (2) there isn't enough innovation. Yes, the six elements are well known, but they are obviously not well understood, since otherwise why would previous researchers mis-identify the effective parts of their own methods? As for a lack of innovation, um, what does that even mean? We did beat everybody else on the benchmarks, you know. Each part of our approach isn't very novel, but put together, we're the best.

After gnashing my teeth for a while, I calmed down a bit and tried to figure out why there has been so much resistance to this paper. I think it's partly because this is very much a non-traditional paper: it doesn't describe a technique nor is it a survey, it's somewhere in between. Also, if you don't read it carefully and think about its implications, it's quite likely that you could finish reading the paper and think, "that's it?" I'd like to believe that if the roles were reversed and I was the reviewer, I'd be able to appreciate this piece of work. But if I'm honest, I'm not 100% sure I wouldn't have a similar reaction.

Anyway, this paper has been submitted to 3 different journals and been rejected each time. At this point, we're kinda sick of swimming uphill, so we're probably going to rewrite it as a "traditional" paper (i.e., "This is how we solved this problem better than anyone else. Any questions?"). There won't be as much analysis and broad insight, but at least it's be more palatable to the average reader. It's better to tell half the story than not have it heard at all.

In case you're interested in reading the paper, the conference version can be found here. By the way, does anyone know if posting the full version of my published papers would violate copyright?

Another journal acceptance! Woo-hoo!

I just received the excellent news that the paper that I wrote in collaboration with Wei Lijun, Zhu Wenbin and my boss Andrew Lim has been accepted for publication in the European Journal of Operational Research. Woot!

This paper had by far the smoothest acceptance procedure out of all the journal papers I have ever written. The reviewer comments came back 3 months after submission with a major revision. It took us a couple of weeks to address the issues, and it took another month for the official acceptance to come through. That's four and a half months from the start of writing to a new line on my CV. :D

It's probably no coincidence that this paper is one of the most straightforward. It deals with the rectangle packing problem, which essentially asks how you can pack a bunch of small rectangles into a bigger rectangle as much as possible. Our main contribution is a heuristic, which is a fancy word for "rules of thumb". Basically, it decides where to place a small rectangle using a number of rules, such as "don't put it too high" and "don't put it where it creates a lot of wasted space where no other small rectangle can fit". We then try the small rectangles in many different orders, and pick the best result. Turns out it works pretty well.

The details are slightly more complicated, and we also deal with another related problem called strip packing, but you get the picture; it's not exactly rocket surgery. On the other hand, it is simple enough for the average software engineer to actually program and use, unlike some of the more complicated papers with lots of math and Greek symbols.

Sometimes, simple really is best. :)

For those of you who actually want to read the paper, it's called "A Skyline Heuristic for the 2D Rectangular Packing and Strip Packing Problems". I'll put a link to it in the Selected Publications page on my website as soon as we get the final proof.

My claims to fame in games

Boy, that first post was pretty depressing, huh? This blog isn't supposed to be all gloomy and serious. I plan to mostly talk about fun and frivolous stuff, like computer games, board games, movies and TV shows. Stuff like that.

So to lighten the mood, here is a partial list of my game-related "achievements", in no particular order.

Chess
- Best Singapore Chess Federation rating: 1775. This was back in 1993 when I was 18, though.
- National Schools Under-16 and Under-18 team champions.
- Best Free Internet Chess Server (FICS) ratings: Blitz 2210, Standard 2108 under the nickname UnsndSac. I lost the password to this account though; my current nickname is ExcuseMe, whose record is not nearly as good.

Magic: the Gathering
- Was 2nd-ranked player in Singapore in 1996.

Boggle
- Current holder of best score of 245 on www.wordrampage.com (nickname UmExcuseMe).

Fantasy Football
- Best finish in fantasy.premierleague.com: 200+; I was as high as 3rd overall before I crashed and burned in the last 8 weeks. See how I did this past season (20,095th position).
- Wrote a monthly "Hot Prospects" article on the FISO forum for 3 seasons. It was reasonably well-received.

So yeah, I've played a lot of games and spent a lot of time on them. I guess that's one of the reasons why I'm 37 years old and still only a postdoc. :P

Looking for a professor job in Singapore

My current postdoc position at the City University of Hong Kong ends in September, so I plan to send out job applications in the next couple of weeks. I'd like to get a tenure-track research professor position in any of Singapore's four universities. Hong Kong is a great place to spend a couple of years to hone my research skills, but I miss the hot and muggy little island where I grew up. The problem is, I can't shake the feeling that I'm in for some major disappointment.

Here's the thing. I got my Ph.D. from the National University of Singapore. Not MIT, not Berkeley, but NUS. There's no concrete proof, but the overriding feeling is that Singaporean universities don't hire Singaporean professors unless they're superstars (I'm realistic enough to admit that although my CV is decent, I'm no Stephen Hawking).

When I told some of my friends that I was looking for a professor job in Singapore, one of them sent me this link to an article on tankinlian.com, which attributes the possible bias against hiring Singaporean professors to the foreigners in charge of the local universities. Another plausible theory is the fact that "ratio of international faculty" is a measure in ranking universities (e.g., QS Rankings, Times Higher Education Rankings). Sure, this measure is only 5% of the total, but why not bump that value up a little?

Anyway, I'll be sending out my job applications and crossing my fingers. If I don't get a bite this time, I'll probably get out of research academics altogether. At 37, it doesn't make sense for me to take another 2 or 3 years to find a university willing to hire me when I can be earning a decent wage in industry starting immediately.